San Antonio Mayor Ron Nirenberg called it a "horrible human tragedy" when he made the statement late Monday night.
A few hours earlier, a worker in a rural area on the outskirts of the Texas city had heard calls for help.
When he got to the truck from which the screams were coming, just before six, the back doors were ajar.
Inside, he saw many lifeless bodies and called 911 - as the authorities describe it.
North American political correspondent based in Washington.
Follow I follow
At 10 p.m., the police confirmed what various media had previously reported: 46 dead migrants were discovered in the truck on the side of the road.
16 other people, including four children, were taken to hospital for treatment.
"We shouldn't open a truck and see bodies stacked inside," said local fire chief Charles Hood at the short-notice press conference.
The task force will be looked after accordingly.
According to him, the truck, which was supposed to have a refrigeration function, was not refrigerated and there was no water.
The weather report for Texas showed up to 39 degrees on Monday.
All of the survivors suffered heat stroke, Hood said.
Nobody was able to leave the truck independently despite the open doors.
One is still "very hopeful" that all of the survivors recovered.
Truck driver not caught
"We hope those who put people in this inhumane position will be brought to justice," Hood said.
Nobody could have imagined what awaited them on the spot.
So far, three men have been arrested, and it is not yet clear whether or to what extent they are involved in the incident.
It appears the driver parked the truck there some time before the discovery;
he is not among those arrested.
According to the police, the truck was not noticed by the security authorities before the emergency call.
A department of the Department of Homeland Security, which primarily deals with migration and human smuggling, has taken over the investigation.
How long the people stayed in the truck, where they started and where the group of mainly young women and men and some children came from, the authorities did not say in the evening, citing the ongoing investigation.
The nearest border crossing to Mexico is around 240 kilometers from San Antonio.
In recent years in Texas, migrants have been found dead in a truck time and time again;
so far, however, not on such a scale.
The non-party mayor Nirenberg spoke of a tragic incident: "We know of 46 people who are dead.
The families had.
Who were probably looking for a better life.
And we have 16 people in the hospital who are fighting for their lives.” The translation for the Spanish media said: “We are very sorry that this happened here.” In the hospital, the survivors would be treated as best as possible.
San Antonio as a transit point for migrants
The disaster is believed to be one of the worst in human smuggling cases in the United States.
The southern state is seeing peak numbers of migrants entering the United States from Mexico this year.
Residents in the area where the truck was found told the Washington Post that migrants are often dropped off there.
San Antonio is a major transit point for migrants traveling from Texas to other parts of the United States.
According to the American newspaper, tens of thousands are said to have passed through the city in recent months.
Texas Gov. Republican Greg Abbott, who is campaigning for his third re-election in November, has made the fight against illegal migration one of his key campaign issues.
On Monday afternoon, he praised an operation he had initiated against illegal migration on Twitter: since it was launched, more than 265,500 migrants have been apprehended and more than 22,000 migrants have been prevented from crossing the border illegally.
Operation Lone Star's website says it is "filling in the dangerous gaps left by the Biden administration's refusal to secure the border."
Later that evening, Abbott blamed President Joe Biden for the incident on Twitter: "These deaths are Biden's account." They were a result of his "deadly open borders policy."
By late evening, Biden had not responded to the accident;
he is currently at the G7 summit in Germany.
The American government itself repeatedly sends the message to migrants not to come to the United States and is working with Mexico to curb illegal migration.
In May, however, the number of attempted and actual border crossings was higher than ever.
At the end of May, despite heavy criticism, especially from the Republican side, the so-called Title 42 regulation, which has been in effect since the beginning of the corona pandemic in March 2020 and largely restricts immigration, should actually fall.
More than 60 percent of attempted border crossings have been refused on this basis in the past two years.
After the corona pandemic, Biden no longer saw any justification for maintaining the regulation.
However, a federal court blocked the project.Keywords: